The present invention relates to a line light source device, a plane light emission device that are preferably used as a backlight of a liquid crystal display panel, e.g., in a portable telephone, a digital camera, or a portable game machine, and a liquid crystal display.
The invention particularly relates to a line light source device that are preferably used as a backlight of a liquid crystal display panel of a portable telephone having a frame reduced in size and thickness and shaped like a narrow picture frame, a personal digital assistant, a digital camera, a portable game machine or the like, a plane light emission device, and a liquid crystal display.
The invention also relates to a plane light source device having a configuration in which a plurality of light emission element units each having a light emission element and a resin part that covers the light emission element are placed in a predetermined two-dimensional pattern without a gap on a surface of a board.
Among conventional line light source devices is one disclosed in JP 2004-235139 A, for example.
FIG. 19A is a perspective view of the line light source device disclosed in the publication, FIG. 19B is a longitudinal section of the line light source device, and FIG. 19C is a section of the line light source device, the section taken along a direction of width of the device. FIGS. 20A through 20F are diagrams illustrating a procedure of a method of manufacturing the line light source device.
FIG. 21 is a perspective view of a plane light emission device having the line light source device, and FIG. 22 is a widthwise section of the line light source device in the plane light emission device.
The line light source device shown in FIGS. 19A, 19B, and 19C, the method of manufacturing the line light source device shown in FIGS. 20A through 20F, and the plane light emission device shown in FIGS. 21, 22 are identical to the line light source device, the method of manufacturing the line light source device, and the plane light emission device that are disclosed in the publication. Therefore, description thereof is omitted.
FIG. 23A is a perspective view of another conventional line light source device, and FIG. 23B is a longitudinal section of the line light source device. FIG. 24 is a section of the conventional line light source device, the section taken along a direction of width of the device. In the line light source device shown in FIGS. 23A, 23B, and 24, light emission elements 1001 on a board 1000 are covered with a resin part 1002 shaped like a simple rectangular parallelepiped.
The plane light emission device shown in FIGS. 21 and 22 is laid on a bottom surface of a liquid crystal display part of a portable telephone, a digital camera, a portable game machine or the like.
The line light source device shown in FIG. 19A has an advantage in that light distribution characteristics of the light source can be adjusted and in that the plane light emission device in which the line light source device is incorporated thus resists producing unevenness in luminance, in comparison with the line light source device that is shown in FIG. 23A and that has light emission elements simply coated with resin. The line light source device has another advantage in that the device resists stripping when undergoing thermal expansion or thermal contraction.
On the other hand, there is a problem in that the device emitting light with high luminance may cause unevenness in luminance, particularly, accompanied by bright lines diagonal to a light incident part of a light guide plate. Necessity of provision of reflector plates therein leads to an increase in number of components, which causes an increase in number of man-hours required for affixation of the components onto the board.